In some applications, it may be desirable to detect the degradation of certain materials. For example, it may be desirable to detect corrosion of rebar in concrete to determine structural integrity, such as in roadways and bridges, for example. Rebar may be defined as a metal rod or bar used for reinforcement in concrete or asphalt pourings.
Near-infrared (NIR) analysis detects and measures the concentration of chloride ions or other corrosion-causing substances in concrete, but it does not report whether the corrosion of rebar actually took place and to what extent. The presence of chloride, or other substances, such as sulphates or carbonates, for example, may cause corrosion, but other factors also play a role, e.g., moisture, pH, the nature of the concrete and rebar, traffic-caused stress, etc.
It may be desirable, therefore, if there were available a simple, low-cost sensor that is capable of detecting and reporting the occurrence and extent of material degradation, such as the corrosion of rebar in bridge decks, for example.